Joining of a polymer and a solid part, which may e.g. be made from metal, ceramic or a polymer, are relevant for a very large number of applications including application of a coating and decorative casings in consumer electronics, insertion of wiring into electronic control boxes, bearings, and many others.
The polymer and the solid part are typically joined either by mechanical joining, e.g. by interlocking, or by adhesion. In often used adhesive methods, a glue is first applied to one or both of the two components to be joined. They are then pressed together to form the completed joint. However, suitable adhesives are commonly associated with long curing times, sensitivity to ambient conditions, such as humidity and temperature, and the need for extensive surface pre-treatment, such as etching or corona treatment. Furthermore, the layer of adhesive fills a gap between the components to be joined, and this additional thickness is undesirable for some applications. In addition, the interfaces obtained with known adhesive methods are prone to degradation over time when exposed to various environmental factors as e.g. humidity and elevated temperatures. Hence, breakage at the interface can occur, resulting in delamination which for industrial use, as highlighted by the medico industry, is unacceptable. In the coating industry the adhesion is often based on interlocking after e.g. sand blasting and physical adhesion.
In addition, there are a range of material combinations that cannot be assembled by the gluing and interlocking methods. In particular cases it is also not desirable to rely on mechanical joints, e.g. ribbon. This may e.g. be due to an increased weight or dimensional constraints. In such cases new and practically invisible joining methods that also allow the combination to withstand extreme environment loads would be highly attractive.
Some of the visions that later resulted in the present invention was presented in the article “The coatings of tomorrow” in “Arsskrift for iNANO”, published February 2008.